Laminated packing and method of forming the same



A ril 1927. p R. H. THORNE LAMINATED PACKING AND METHOD OF FORMING THE, SAME Filed Dec.

INVENTOR ROBERT H. THORNE.

WITNESSES A TTORNEYS Patent ed Aprd 19, 1927 UNITED STATES PATENT OFFICE.

ROBERT HARRY THORNE, OF WILLIAMSPORT, PENNSYLVANIA.

LAMINATED PACKING AND METHDD OF FORMING THE SAME. I

Application filed December 30, 1921. Serial No. 525,822.

laminated packing as utilized in packing cups for pistons or plungers, my object generally being the promotion of a construction as well as the method of forming a packing of this character which will avoid crinkling of the finished product due to undue stretching of the fabric material of which it is formed, and to avoid the present difiiculty with respect to ravelling of the threads of the fabric material in the course of manufacture. I 1

Generally speaking, the present method of forming an article-from which the present invention relates, consists of superimposing layers of fabric alternately with layers of unvulcanized rubber, then temporarily at; taching the several layers to one another, applying great pressure thereto in order to force the rubber through the interstices of the woven fabric material, then die-pressing the adhering layers to the desired form of the packing, then vulcanizing the packing and finally punching and trimming.

In this process the layers of fabric ma.- tcrial are superimposed in a promiscuous manner in so far as the run of the threads of the material of which the layers are formed is considered, and the result is-that a considerablc portion of finally imperfect product due to crinkling, which I have found to result from the unequal stretching of the fabric material during the die-pressing op eration. There is, furthermore, a considerable disadvantage at present in that when the layers are attached, as well as during the subsequent steps before vulcanization, there is considerable danger of excessive ravelling at the edges of the layers likely. to result in a weakened edge in the final product where the greatest possible strength is desired.

-My invention avoids these disadvantages in the manner which I will proceed to describe with reference to the accompanying drawing forming a part of this specification, and wherein Figure 1 is a perspective view showing sections of material from which the layers are cut; p

- Figure 2 is a perspective view showing a series of layers of fabric and unvulcanized rubber before their alternating arrangement; I Figure 3 is a perspective view showing the arrangement of alternate layers of fabric and rubber as well as themanner in which they are temporarily connected before being vulcanized; I

- Figure 4 is a cross section through a portion of Figure 3;

Figure 5 is a section taken diametrically through the finished packing;

Figure 6 isa perspective view showing a paiir of layers with their edges unravelled, an

Figure 7 is a top plan View showingin particular the manner in which the layers are superimposed according to my invention. 1

The method of forming laminated vulcanized packing of the type shown in Figure 5, and in the nature of a packing cup 10 for pistons, involves the cutting of circular sections of fabric such as indicated at 11, in Figure 2, from wovenfabric material 12, as indicated in Figure 1, and also the cutting of slightly smaller circular sections 13 of unr vulcanized rubber. The cup sections 11 of the fabric are then superimposed in desired number upon one another with interposed and alternating layers 13 of rubber in the manner seen in Figure 3, and the several alternating layers are then temporarily at tachedby stitching, as for instance a circular' row of stitches 14, seen in Figure 3, and

also in Figure 4. The body of the packing is thus formed and is then placed under high pressure sufficient to force the rubber through theinterstices of the woven fabric so as to form a substantially homogeneous mass, which is then pressed to the ultimate form of the desired packing 10 by the use of dies and subsequently vulcanized, the central-portion being cut away to form a rod or valve body receiving aperture 15, and the opposite edge being cut and trimmed, to form the bevel 16. 7

This process as at present carried out and as above stated, 'is open to certain objecv tions, one being the rather high percentage of imperfect products due to crinkling of the wall of the finished packing 10 arising from the unequal stretching of the fabric layers 11 during the die-pressin operation, and another being the susceptibility of the edges of the fabric edges of the section 11 to unravelling while they are being assembled,

' as in Figure 3, and in fact subsequent to this assembly and at any time before vulcanization. This latter disadvantage results i Ell quently in a weakened bevelled edge 16 upon the linished product Where great strength is particularly desired.

According to my invention, material 12, or which the layers ll are initially cut, is

'woven in the first instance "with threads preterahly Warped. threads ll" of a distinctive readily visible color diderent trom that of the other threads, so as to thus provide means whereby the run of the threads is apparent, these distinctively colored threads ll occurringat sufficiently trequent intervals to insure at least two distinctive threads in each of the disks or layers ll, as will be apparent train the inspection at igs. 2, 3, it and "t.

In super-posing the layers ll With the interposed layers ct ruhher 13 the layers ll so disposed in relation to one another that the distinctively colored threads 1'? in successive layers are disposed at angles with respect to one another, this losing obvious trorn an inspection or lFigs. 3 and 7, the latter of which in particular indicates hy brolren lines the directions oil extension ot the threads of the shccessive layers of the series. lln this Way the run ot the threads of the successive layers losing turned in difi erent directions, the stretching of the connected layers, especially when the rubber has been thoroughly dispersed through and be tween the threads thereof during the pressure operation, is evenly distributed so that during the die-pressing operation this even stretching entirely around the packing body will avoid the frequent crinkling now enr eaaaoa countered in view of the unequal stretching on account ot the superposing of layers having the run of the threads parallel throughout the loody.

Moreover, it is obvious that where layers are superimposed with the run of the threads in the same direction they are readily susceptible to unravelling ot the edges as indicated in Figure G, which is defeated Where they are superimposed according to my invention as just above described.

lily thus avoiding crinlrling I do away with considerable Waste encountered at present and the necessity ot discarding imperlect products, and by avoiding); ot retelling ot the edges 1 insure the presence of a bevelled edge 16 on the finisl ied product having maniinuin' strength after cutting and trimming- I claim ll. method oft :torming laminated packing which consists in utilizing :tabric layers having distinguishingly colored threads constitoting visible means indicating the run of the threads thereof, superimposing the layers with alternate layers of unvulcanized rubber and with the run of the threads of each or the several layers as shown by said indicating means is at an angle to those of the several other layers to avoid unravelling and unequal stretching, compressing the layers together under heavy pressure, diepressiug the compressed layers to the required form and then vulcanizing and subsequently trimming the vulcanized ackin nonnnr HARRY r onm'if 

